The present invention relates generally to a device for handling a gas, such as oxygen and nitrous oxide, under high pressure. The present invention also relates to a valve for controlling the flow of gas and to a system for reducing or preventing high pressure surge.
Known high pressure oxygen delivery systems are provided with an oxygen cylinder, a cylinder valve and a pressure regulator. The oxygen cylinder may be charged with pure oxygen at a pressure of two thousand two hundred pounds per square inch (psi) or more in the United States and over three thousand psi in other countries. The valve is attached to the cylinder to stop the flow of oxygen to the regulator. The pressure regulator is designed to reduce the tank pressure to under two hundred psi. Most pressure regulators in the United States reduce tank pressure to approximately fifty psi. Typical pressure regulators in Europe reduce tank pressure to approximately sixty psi.
When the valves in the known oxygen systems are opened rapidly, undesirable high pressure surges may be applied to the pressure regulator. There is a need in the art for preventing such high pressure surges, as well as increases in the temperature of the gas which may result in ignition. A similar problem may occur with respect to nitrous oxide supplied, for example, for dental procedures.
The risk of oxygen regulator failure may be higher for portable oxygen systems that are used in adverse environments and/or by untrained personnel. Portable oxygen systems are used for emergency oxygen delivery at accident sites; for other medical emergencies, such as heart attacks; and for transporting patients. Homecare patients who use oxygen concentrators as the main source of oxygen for oxygen therapy are required to have standby oxygen cylinders in case of power failures. Oxygen cylinders are also used to provide homecare patients with mobility outside the house. There is a need in the art for a valve that can be used easily in such portable systems and that reduces or eliminates the occurrence of high pressure surges. Other uses include hospitals, where oxygen cylinders are used to transport patients. They are also used as emergency backup systems.
Known surge suppression devices are illustrated in U.S. Pat. Nos. 3,841,353 (Acomb), 2,367,662 (Baxter et al.), and 4,172,468 (Ruus). These devices all suffer from one or more of the following drawbacks: relatively massive pistons resulting in slower response times, relatively elongated bodies, complicated construction resulting in increased cost, or construction preventing positioning of the devices in different locations in existing systems.
Acomb discloses an anti-surge oxygen cylinder valve in which the surge-suppression device is integrated with the cylinder valve. The device referred to by Acomb requires a force opposed to a spring force to function. In the Acomb device, the opposing force is provided by a stem connected to the valve handle. Additionally, if the bleeder orifice becomes plugged, the valve does not allow flow, and the gas supply is not available for use. In that case, the user may interpret the tank to be empty when it is full, with the danger that such a misunderstanding brings.
Baxter discloses a pressure shock absorber for a welding system. Baxter refers to a piston that is elongated with a bore through the center. The elongated piston results in an increased moment of inertia that increases the time in which the piston reacts to a pressure surge. The long bore results in necessarily tighter tolerances for controlling the gas flow rate through the bore. In addition, the placement of the spring abutting the elongated piston results in a relatively large device.
Ruus discloses a pressure shock absorber for an oxygen-regulator supply system with an elongated, two-part piston. The elongate construction of the piston results in an increased moment of inertia that increases the time required for the piston to react to a pressure surge. The two-part piston results in increased complexity and manufacturing cost. Also in this device, if the restricted passageway becomes plugged, no flow is allowed and the device suffers from the same potential for user misinterpretation as the Acomb device.